1. Field of the Invention
The present invention relates to a field emission display (FED), and more particularly, to a field emission display having a field emission source formed of carbon nanotube.
2. Description of the Related Art
Recently, the use of carbonaceous materials as a field emission source of a field emission display (FED) has been actively developed. In particular, among the carbonaceous materials, carbon nanotube has been expected as an ideal field emission source because it has an extremely fine edge having a radius of about 100 xc3x85, enabling the emission of electrons even under a voltage of 10xcx9c50V.
In general, a diode FED employing carbon nanotube as the field emission source (hereinafter, referred to as xe2x80x9ccarbon nanotube emitterxe2x80x9d) includes cathode electrode and anode electrode respectively disposed on a pair of substrate, and carbon nanotube emitter and phosphor layer respectively disposed on the cathode electrode and the anode electrode.
The diode FED as described above has, however, disadvantages because it is difficult to apply high voltage needed to accelerate electrons to the anode electrode, so the brightness of a screen is not sufficient. Also, it is difficult to precisely control an emission current of the carbon nanotube emitter, so it is hard to display multi-gradation images.
A conventional triode FED further includes gate electrode to control the field emission of the carbon nanotube emitter. The triode FED has, however, disadvantages because the cathode and gate electrodes are easily short-circuited via the carbon nanotube emitter when depositing the carbon nanotube materials on the cathode electrode.
Further, the above-mentioned diode and triode FEDs have a problem, because the electrons emitted from the carbon nanotube emitter diverge and activate other phosphor pixels as well as corresponding phosphor pixel.
It is an objective of the present invention to provide a field emission display device capable of operating under a low driving voltage and converging electrons toward corresponding phosphor pixel.
It is another objective of the present invention to provide a field emission display device that has an advantage in realizing a large-sized display and simplifying the manufacturing procedure thereof.
To achieve the above objectives, the present invention provides a field emission display device including a substrate, an anode electrode formed on the substrate, an insulation layer disposed on the substrate covering the anode electrode except a pixel area to be formed on the anode electrode, a phosphor layer disposed on the pixel area to be in contact with the anode electrode, a cathode electrode formed on the insulation layer between the phosphor layers, and a carbon nanotube emitter disposed on the cathode electrode for emitting electrons toward at least one of the phosphor layers.
Preferably, the anode electrode and the cathode electrode have a structure of plural line patterns and intersect each other at right angles.
Preferably, the carbon nanotube emitter corresponding each phosphor layer is arranged at the same intervals as the phosphor layers covering at least one edge of the cathode electrode.
Alternatively, the carbon nanotube emitter is disposed in a line pattern covering at least one edge of the cathode electrode.
Further, the present invention provides a field emission display device including a substrate, an anode electrode formed on the substrate, an insulation layer disposed on the anode electrode except a pixel area to be formed on the anode electrode, a gate electrode disposed within the insulation layer except the pixel area, a phosphor layer disposed on the pixel area to be in contact with the anode electrode, a cathode electrodes formed on the insulation layer between the phosphor layers, and a carbon nanotube emitter disposed on the cathode covering at least one edge of the cathode electrode for emitting electrons.
Preferably, the field emission display device of the present invention further includes a front substrate which is coupled with the substrate by a sealant. The space formed between the two substrates is kept as vacuum. Further, the front substrate has a transparent electrode to reduce the divergence of the electrons emitted from the carbon nanotube emitter.